Numerous conventional processes require that materials be successively exposed to jets from one or more nozzles or nozzle arrays. The jets may comprise solid particles, liquids, slurries, or gas (such as high-pressure air). An important example of this type of process occurs during the manufacture of electronic components, such as integrated circuit leadframes and similar components.
In the electronic component industry, discrete or integrated components are typically encapsulated in an electrically insulating material such as a plastic or ceramic package. Metal contacts or leads generally protrude from the package. These contacts or leads typically require deflashing or other chemical treatment before or after encapsulation.
It is conventional to accomplish such treatment by loading the parts onto racks or into baskets, and sequentially exposing the racks or baskets to jets from a number of nozzles or nozzle arrays, by translating the racks or baskets past the nozzles. The jets typically include a jet comprising a deflashing slurry, one or more rinsing jets (which may comprise water or a cleansing solution), and one or more drying jets (which may comprise air).
It is conventional to employ a conveyor (which may include a chain belt drive) to translate the racks past the nozzles. However, conventional conveyors may undesirably transfer substantial amounts of the deflashing slurry to subsequent processing stations, and may rapidly wear out due to exposure to the deflashing slurry. To avoid these problems, some conventional system have employed at least two isolated and distinct conveyors, rather than a single conveyor for translating each product being treated past all treatment stations. In this type of multi-conveyor system, the products undergoing treatment must be transferred from at least one conveyor (which may be exposed to a deflashing slurry) to at least one other conveyor (which is positioned so as not to be exposed to the slurry).
In general, conventional material handling systems embody all or some of the following disadvantages: complexity, in the sense that complex mechanical components (such as shafts, belts, isolation joints, and the like) are required to transfer the products being treated between distinct conveyors; complexity, in the sense that extremely accurate positioning mechanisms are required for loading and unloading the products onto and off each conveyor; limited conveyor lifetime due to exposure to corrosive, abrasive, or otherwise harsh jets from nozzles; inability to transport products having a wide range of shapes and sizes without system modifications; low production rate, because the products being treated are oriented with their longitudinal axis parallel to their travel path so that few products are processed per unit length of the product travel path; and unreliability, in the sense that a percentage of the products being transported, especially delicate products such as electronic components, are damaged during the loading and unloading processes or lost during transportation along the process path.
Until the present invention, it was not known how to transport materials for sequential exposure to jets from nozzles or nozzle arrays in a manner eliminating all the mentioned disadvantages.